An 11-year-old girl in Seminole County, Ga., was killed Wednesday afternoon when thrashing winds sent a car or boat port airborne onto the family's mobile home, Fox News has confirmed. The girl, whose identity has not been released, was hit by the structure as it tore through the home's roof.

Authorities told WMAZ-TV that first responders didn't reach the home until after nightfall due to downed trees and power lines blocking their way.

Search and rescue crews were expected to escalate efforts to reach hardest-hit areas and check for anyone trapped or injured in the storm debris.

Florida Gov. Rick Scott said crews were working on clearing roads so that first responders could reach those impacted by the storm.

The powerful storm made landfall as a Category 4 hurricane Wednesday afternoon and ripped through the Florida Panhandle with 155 mph winds and 12-foot waves.

Rick Reichmuth, Fox News' chief meteorologist, said Michael was the fourth most powerful storm to ever make landfall in the U.S. in terms of wind, and the third most powerful in terms of pressure, at 919 mb. It was the first storm of its magnitude to make landfall in the Panhandle since record-keeping began 1851.

Damage in Panama City was so extensive that broken and uprooted trees and downed power lines lay nearly everywhere. Roofs were peeled away, sent airborne, and homes were split open by fallen trees. Twisted street signs lay on the ground.

More than 380,000 homes and businesses in Florida were without power at the height of the storm.

Georgia Power said that nearly 300,000 customers have lost power as Michael sweeps across the state Thursday morning, WSB-TV reported.

Meanwhile, Michael continues its track across central and eastern Georgia toward the Carolinas, still reeling from flooding by last month's Hurricane Florence.

The storm, which has sustained winds of 50 mph, was about 30 miles west of Augusta, Ga., and 90 miles northeast of Macon, the National Hurricane Center said in a 5 a.m. ET advisory.

According to the agency, strong winds, heavy rain and tornadoes are expected across parts of Georgia, South Carolina and North Carolina through Thursday. Rainfall of 4-7 inches could inundate parts of Georgia, which could also see flash-flooding.

Although the storm is steadily weakening, Tropical Storm Warnings remain in effect for southeastern Georgia and much of the Carolinas.

Michael is forecast to move off the Mid-Atlantic coast by early Friday, the NHC said.